Devices and method for smelterless recycling of lead acid batteries

ABSTRACT

Lead from lead acid battery scrap is recovered in two separate production streams as clean grid lead and as high-purity lead without smelting. In preferred aspects, lead recovery is performed in a continuous process that uses an aqueous electroprocessing solvent and electro-refining. Spent electroprocessing solvent and/or base utilized to treat lead paste from the lead acid battery scrap can be recycled to the recovery process.

This application is a divisional application of allowed U.S. patentapplication with the Ser. No. 15/527,749, filed May 18, 2017, which is a371 application of PCT Application No. PCT/US15/30626, filed May 13,2015, which is a continuation-in-part application of PCT Application No.PCT/US14/66142, filed Nov. 18, 2014, which further claims priority toU.S. provisional application with the Ser. No. 61/905,941, filed Nov.19, 2013.

FIELD OF THE INVENTION

The field of the invention is recycling of lead acid batteries,especially as it relates to devices and methods that utilize aqueoussolutions and do not require smelting and that can be performed incontinuous fashion.

BACKGROUND OF THE INVENTION

The background description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

Lead acid batteries (LABs) are the single largest class of batteriesused today. They are essential for applications ranging from startingautomobile engines, providing emergency back-up power for data centers,and powering industrial and recreational vehicles such as fork lifttrucks and golf carts. Unlike any other battery type, LABs are almost100% recycled and this feature puts lead as the single most recycledcommodity. While LAB production is increasing at an average rate ofabout 5% per year globally, production of new lead from ore is becomingincreasingly difficult as lead rich ore deposits as depleted. Notsurprisingly, new and more efficient methods for lead recycling areurgently needed.

Unfortunately, all or almost all of the current lead recycling from LABsis still based on lead smelting technology, originally developed over2000 years ago to produce lead from ore bodies. Lead smelting is apyro-metallurgical process in which lead, lead oxides, and other leadcompounds are heated to about 1600° F. and then mixed with variousreducing agents to remove oxides, sulfates, and other non-leadmaterials. Prior Art FIG. 1 depicts a typical smelting operationstarting with ground up LAB materials.

Unfortunately, lead smelting is a highly polluting process, generatingsignificant airborne waste (e.g., lead dust, CO₂, arsenic, SO₂), solidwaste (lead containing slag), and liquid waste (e.g., sulfuric acid,arsenic salts), and pollution issues have forced the closure of manysmelters in the US and other Western countries. Migration and expansionof smelters in less regulated countries has resulted in large scalepollution and high levels of human lead contamination.

To complicate matters, obtaining permits for lead smelters has becomeincreasingly difficult, and smelting plants are generally expensive tobuild and operate. Consequently, profitable operation of smelters is afunction of scale. As such, there is a drive towards larger and morecentralized smelters, which is at odds with the logistics of the LABindustry that favors distributed recycling and production located closeto concentrations of LAB use. As a result, only the largest LABproducing companies have been able to justify and operate smelters whileother companies rely on secondary lead producers to recycle theirbatteries and supply them with lead. This can make it difficult for LABproducers to meet increasingly stringent requirements for “cradle tograve” control of their products, such as the international standard ISO14000.

On a more technical level, it should be appreciated that lead smeltingwas developed to produce lead from lead ore (primarily Galena or leadsulfide). However, the chemistry of recycled lead acid batteries isvastly different to the chemistry of lead smelting of ores. As such leadsmelting is a fundamentally inefficient process for lead recycling.

Various efforts have been made to move away from smelting operations andto use more environmentally friendly solutions. For example, U.S. Pat.No. 4,927,510 (to Olper and Fracchia) teaches recovering in pure metalform substantially all lead from battery sludge after a desulfurizationprocess. All applications and publications identified herein areincorporated by reference to the same extent as if each individualpublication or patent application were specifically and individuallyindicated to be incorporated by reference. Where a definition or use ofa term in an incorporated reference is inconsistent or contrary to thedefinition of that term provided herein, the definition of that termprovided herein applies and the definition of that term in the referencedoes not apply. Unfortunately, the '510 patent still requires use of afluorine containing electrolyte, which is equally problematic.

To overcome some of the difficulties associated with fluorine containingelectrolyte, desulfurized lead active materials have been dissolved inmethane sulfonic acid as described in U.S. Pat. No. 5,262,020 (toMasante and Serracane) and U.S. Pat. No. 5,520,794 (to Gernon). However,as lead sulfate is rather poorly soluble in methane sulfonic acid,upstream pre-desulfurization is still necessary and residual insolublematerials typically reduced the overall yield to an economicallyunattractive process. To improve at least some of the aspects associatedwith lead sulfate, oxygen and/or ferric methane sulfonate can be addedas described in International Patent Application Publication No. WO2014/076544 (to Fassbender et al), or mixed oxides can be produced astaught in International Patent Application Publication No. WO2014/076547 (to Fassbender et al). However, despite the improved yield,several disadvantages nevertheless remain. Among other things, solventreuse in these processes often requires additional effort, and residualsulfates are still lost as waste product. Moreover, during process upsetconditions or power outage (which is not uncommon in electrolytic leadrecovery), the plated metallic lead will dissolve back into theelectrolyte in conventional electrolytic recovery operations, unless thecathode was removed and the lead peeled off, rendering batch operationat best problematic.

Thus, even though numerous methods for lead recycling are known in theart, all or almost all of them, suffer from one or more disadvantages.Therefore, there is still a need for improved devices and method forsmelterless recycling of lead acid batteries, especially in a continuousmanner.

SUMMARY OF THE INVENTION

The inventive subject matter is directed to various devices, systems,and methods of lead battery material processing in which anelectroprocessing solvent is used to selectively dissolve the activematerial lead (e.g., PbO, PbO₂, and in certain embodiments PbSO₄) forrecovery of metallic lead while recycling and re-using solvents andother necessary reagents within the process. The dissolved lead isrecovered by electrodeposition, preferably in a continuous fashion,while clean solid grid lead is recovered from the lead ion-enrichedelectroprocessing solvent.

In one embodiment of the inventive concept, lead materials are recoveredfrom lead acid batteries by contacting active material lead with anelectroprocessing solvent to generate an electroprocessing solvent withsolvate lead ions and solid lead (for example, a lead grid from such abattery). Solid lead is removed from the solvent, and solvated lead ionsare reduced on a cathode to provide high purity metallic lead. Thisreduction of lead ions also regenerates the electroprocessing solvent.In some embodiments sulfur is extracted from the active material lead bytreatment with a base, which generates a soluble sulfate. The base isrecovered from this soluble sulfate, and is recycled in the process forextraction of sulfate. Suitable electroprocessing solvent include analkane sulfonic acid, typically between 5% and 50% by weight, and insome embodiments include a chelator in amounts of 0.5% to 20% by weight.In some embodiments high purity lead is removed as lead ions are beingreduced, for example by moving the cathode relative to the lead ionenriched electroprocessing solvent. Such high purity lead is in the formof a micro- or nano-porous mixed matrix that has a density of less than5 g/cm³. Reduction of lead ions provides a regenerated electroprocessingsolvent that is recycled into the process by contacting it with leadmaterials. In some embodiments sulfate and/or metal ions other than leadare removed from such regenerated electroprocessing solvent. In stillother embodiments the steps of providing lead materials, contacting thelead materials, removing at least some of the grid lead, and reducinglead ions are performed to allow processing in a continuous fashion.

Another embodiment of the inventive concept is a method for continuouslyproducing high quality lead (e.g. 98% or greater purity) from lead ionssolvated in an electroprocessing solvent. A cathode is used to reducelead ions in such a solvent to form an adherent high purity lead whileregenerating the electroprocessing solvent. The high purity lead isremoved from one part of the cathode while lead ions are reduced onanother part of the cathode, for example by moving the cathode relativeto the electroprocessing solvent. The regenerated solvent, in turn, isused treat lead materials to produce a lead ion enrichedelectroprocessing solvent suitable for producing high quality lead. Insome embodiments sulfur is extracted from active material lead using abase, to generate a soluble sulfate salt. The base used for sulfurremoval is recovered from the soluble sulfate salt, and this recycledbase re-used to extract sulfur from active material lead. Suitableelectroprocessing solvents include an alkane sulfonic acid in an amountbetween 5% and 50% by weight. In some embodiments electroprocessingsolvents include a chelator in an amount between 0.5% and 20% by weight.The high purity lead is produced as a micro- or nanoporous mixed matrixwith a density of less than 5 g/cm3, and is collected from the cathodein a non-peeling fashion by a harvester positioned proximal to thecathode. In some embodiments sulfate and/or metal ions other than leadare removed from the regenerated electroprocessing solvent.

Another embodiment of the inventive concept is a production intermediatethat includes an aqueous solution of an alkane sulfonic acid (at between5% and 50% by weight), dissolved, base-treated active material lead, andundissolved, solid grid lead. Such base-treated active material lead isessentially or completely desulfurized. In some embodiments the alkanesulfonic acid is methane sulfonic acid and is present at between 15% and30% by weight.

Another embodiment of the inventive concept is a lead composition thatincludes metallic lead with a purity of 98% or greater, molecularhydrogen, and an electroprocessing solvent that is free of chelators.The lead composition is in the form of a micro- or nano-porous mixedmatrix with a density of less than 5 g/cm³, and in some instances lessthan 3 g/cm³. In some embodiments the electroprocessing solvent includesan alkane sulfonic acid (for example, methane sulfonic acid) at aconcentration of between 5% and 50% by weight.

Another embodiment of the inventive concept is an electrolyzer forproducing high quality lead using an electroprocessing solvent. Such anelectrolyzer includes an anode and a cathode in an electrodepositioncell that places the anode and cathode (in some instances without anintervening separator) in contact with a lead ion enrichedelectroprocessing solvent. For example, the cathode can be a rotatingdisc that moves at a speed that allows the formation of adherent highpurity lead as a micro- or nano-porous mixed matrix on the cathode. Insome embodiments the cathode can move relative to the electroprocessingsolvent. It also includes a lead harvester that is positioned proximalto a surface of the cathode and that is shaped and arranged to collecthigh purity lead that is adherent to the cathode's surface in anon-peeling manner. In some embodiments the anode is made from titaniumand is coated with ruthenium oxide and the cathode is aluminum. In someembodiments the electrolyzer also includes a solvent conditioning unitthat is configured to remove sulfate and/or metal ions other than leadfrom the electrodeposition solvent. In other embodiments theelectrolyzer includes an electrochemical cell containing a solublesulfate salt, and that is configured to produce a sulfuric acid and abase.

Another embodiment of the inventive concept is a method of recycling alead acid battery. In such a method a lead paste that includes leadsulfate is obtained from the battery and contacted with a base to for asupernatant and a lead hydroxide containing precipitate. The supernatantis treated in an electrochemical cell to generate sulfuric acid and aregenerated base. The precipitate is treated with a solvent to generatea lead ion solution, which is in turn contacted with a collectioncathode. An electrical potential is applied to the collection cathode toreduce the lead ions, depositing metallic lead on the collection cathodewhile regenerating the solvent. Lead is collected from the collectioncathode while the regenerated base is recycled in the process to treatadditional lead paste. Similarly, the regenerated solvent is used totreat the lead hydroxide containing precipitate formed from theadditional lead paste. In some embodiments the solvent solution includesan alkane sulfonic acid and does not include a chelator.

Various objects, features, aspects and advantages of the inventivesubject matter will become more apparent from the following detaileddescription of preferred embodiments, along with the accompanyingdrawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

Prior FIG. 1A is a schematic of a conventional smelting process forground lead acid battery materials.

FIG. 1B is an exemplary schematic of a smelter-less process for groundlead acid battery materials according to the inventive subject matter.

FIG. 1C is an exemplary schematic of an electrolyzer according to theinventive subject matter.

FIG. 2 is an exemplary schematic of a closed loop smelter-less processfor recovery of materials from lead acid batteries.

FIG. 3A is an exemplary experimental set up for a process according toFIG. 1B.

FIG. 3B is a detail view for an electrolyzer with a disc-shaped cathodeand a lead product in a micro- or nanoporous mixed matrix.

FIGS. 4A-4C are graphs illustrating current efficiencies (CE) as afunction of lead concentration (4A, 4C) and current density (4B) usingan electrolyzer according to the inventive subject matter.

DETAILED DESCRIPTION

The inventors have now discovered that lead acid battery materials canbe recycled in a conceptually simple, yet effective manner where alllead materials are treated with an electroprocessing solvent that helpsclean grid lead materials, and especially grids and contacts/bus bars.In some embodiments the electroprocessing solvent dissolves all activelead materials, including lead oxide and lead sulfate. In otherembodiments sulfate is extracted from active lead materials by basetreatment prior to solvation of lead species in the electroprocessingsolvent, providing a base treated active material that is desulfurizedor essentially desulfurized (i.e. less than 1% sulfate content). Such anelectroprocessing solvents can, upon loading with lead ions due toactive materials dissolution, be subjected to an electrodepositionprocess that allows continuous production of high-purity metallic leadwhile regenerating the electroprocessing solvent for a further cycle. Inaddition, sulfate recovered by base treatment can be treated in anelectrochemical cell to regenerate the base for a further cycle, therebyproviding a closed loop system.

With respect to continuous lead recovery it should be especiallyappreciated that heretofore known processes would plate metallic leadfrom an electrolyte onto a cathode in an acidic solution. During processupset conditions or power outages (which are not uncommon inelectrolytic lead recovery), the plated metallic lead would dissolveback into the electrolyte unless the cathode was removed and the leadremoved. Still further, conventional electrolytic lead recoveryprocesses deposit or plate lead as a strongly bound film to the cathode,which makes removal of the lead labor intensive. For example, lead canbe peeled from the cathode as thin, plated sheets that adhere to thecathode's surface. However, such sheets have the tendency to break orflake, and lead removal is thus inefficient and/or cumbersome. Incontrast, the lead recovery using the devices and methods according tothe inventive subject matter will allow recovery of high purity lead ina non-peeling manner. For example, the lead product can be removed fromthe cathode as a non-film material (e.g., as amorphous micro- ornanoporous mixed matrix) using a simple wiper or scraper (preferablywhere the scraper does not directly contact the cathode but is in closeproximity, e.g., between 0.5 and 5 mm) as a removal tool, which in turnallows continuous removal on one portion of the cathode while reductionis performed at another portion of the cathode.

In some aspects of the inventive subject matter, the electroprocessingsolvent comprises an alkane sulfonic acid in combination with achelator, and most preferably methane sulfonic acid and EDTA. Theinventors surprisingly discovered that all relevant lead species foundin active material lead are effectively and quickly dissolved in MSA(methane sulfonic acid) where the MSA includes substantial quantities ofa chelator at an acidic pH (i.e., at a pH equal or less than 7.0, equalor less than 6.0, equal or less than 5.0, equal or less than 4.0, orequal or less than 3.0). For example an aqueous solution of MSA and EDTAdid dissolve positive active material (e.g., lead sulfate, andespecially tri/tetrabasic lead sulfate; PbSO4.3PbO.H2O/PbSO4.4PbO.H2O)as well as negative active material (e.g., lead oxide ranging fromPb(II) to Pb(IV) and multiple partial oxidation states between them).Moreover, it was observed that under dissolving conditions for theactive material lead, grid lead (e.g., metallic lead from contacts, busbars, lead alloys for battery grids, etc.) is not dissolved but insteadcleaned by such an electroprocessing solvent. Such finding wasparticularly unexpected as known processes involving lead dissolution inMSA characterized lead sulfate as being only sparsely soluble in MSA.Therefore, among other benefits of using a chelator (and especiallyEDTA) in MSA, it should be noted that EDTA synergistically anddramatically enhanced solubility of lead sulfates in MSA. Consequently,it should be recognized that using the electroprocessing solvent of theinventive subject matter, active material lead can be processed withoutthe need for prior desulfurization.

Alternatively, in other embodiments of the inventive concept theelectroprocessing solvent includes an alkane sulfonic acid (preferablymethanesulfonic acid or MSA) but does not include a chelator. Inprocesses utilizing such a chelator-free solvent, active lead materialsare treated with a base (for example, LiOH, NaOH, and/or KOH) togenerate soluble sulfate salts and insoluble lead hydroxide from thelead sulfate component of the active lead material. Such a base-treatedactive lead material includes lead oxides and lead hydroxide that can becollected as a lead containing precipitate. The lead oxides and leadhydroxide of the lead containing precipitate are soluble in alkanesulfonic acids (such as MSA); as a result, in such a method the use of achelating agent with the alkane sulfonic acid is not necessary.

The soluble sulfate salt generated by base treatment is readilycollected as a supernatant and can be processed (for example in anelectrochemical cell) to regenerate the base species used for treatmentof the active lead material. This advantageously closes the loop forbase usage in such a process. Treatment of the supernatant in anelectrochemical cell also generates sulfuric acid, which has numerousindustrial uses (including production of new lead acid batteries).

Additionally, the inventors also unexpectedly noted thatelectroprocessing solvents comprising an alkane sulfonic acid with orwithout a chelator (such as MSA or MSA+EDTA) are suitable forelectrolytic recovery of lead on a cathode. Notably, such recovery couldeven be performed in an electrodeposition cell without a separator andas such significantly simplified the design of suitable electrolyzers.Such finding was particularly unexpected as prior reports on lead acidbatteries having MSA as electrolyte (SLABs) noted that layers of aninsoluble form of PbO₂ would form on the anode, which effectively shutsdown the SLAB battery.

While EDTA has been used to preferentially dissolve lead salts and tosupport lead electrochemical plating from solution as described in U.S.Pat. No. 7,368,043 (to Mohanta et al), such plating requires a complexand expensive electrochemical cell with a membrane separator to inhibitdestruction of the EDTA. Still further, such process also operates athigh pH (caustic pH) and it would be impractical to convert all of theactive material from a LAB to caustic on a commercial basis. Incontrast, EDTA in combination with the MSA at acidic pH not onlyincreased solubility of most lead species, and especially lead sulfates,but also allowed for reduction of ionic lead to an adherent, but notplated form. Similarly, reduction of ionic lead from MSA in the absenceof chelators (i.e. following base treatment of active lead materials andMSA solvation of precipitated lead species) also permitted recovery ofmetallic lead as an adherent, but not plated, form.

As used herein, the terms “adherent” or “weakly associated” inconjunction with metallic lead that was formed by reduction of ioniclead refers to a form of lead that is not a coherent film over thesurface of the cathode, but that is amorphous and can be wiped off thecathode. In other words, a weakly associated or adherent lead productdoes not form in a macroscopic dimension intermetallic bonds between thecathode and the lead product and will therefore not form a coherent leadfilm on the cathode. For example, by observation in most experiments(e.g., see experimental description below), lead formed in a spongy lowdensity layer that was loosely attached to the cathode, floated off astatic plate cathode, and could be washed off the surface of a rotatingcathode if electrolyte circulation was too aggressive. Moreover, alkanesulfonic acid without chelator (e.g., MSA) and the combination of thealkane sulfonic acid and chelator (e.g., MSA+EDTA) allowed for stableelectrolytic recovery of lead without significant destruction of thealkane sulfonic acid (e.g., MSA) or the chelator (e.g., EDTA). Thisregeneration of both alkane sulfonic acid or alkane sulfonicacid+chelator electroprocessing solvents permits their re-use in asuccessive cycle of their respective processes, advantageously closingthe loop for electroprocessing solvent utilization in methods of theinventive concept.

Therefore, it should be appreciated that lead acid batteries and batterymaterials can be processed as exemplarily depicted in FIG. 1B by firstcrushing or grinding the battery or battery materials to a relativelysmall size (e.g., average particle size between 0.1 and 1 cm, or between1 and 3 cm, or between 3 and 5 cm, or larger, in the largest dimension),followed by removal of plastic parts and battery acid (which can befurther recycled or processed). The so obtained lead scrap material willpredominantly contain grid lead and active material lead, which is thentreated in a container with the electroprocessing solvent to clean thegrid lead and to dissolve the active material lead. After a suitableperiod of lead dissolution (or upon complete dissolution of the activematerial lead), remaining cleaned solid grid lead can be extracted fromthe solution, optionally washed, and pressed into lead chips/ingots toso yield grid lead that can be directly reused or further refined. Therecitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein.

The so obtained lead ion-enriched solution may then be treated to removeother non-lead ions (e.g., zinc, calcium, tin, silver, etc.), which maybe performed using a selective ion exchange resin, other selectiveadsorbent, selective electrodeposition, liquid chromatography and/orprecipitation. Of course, it should be recognized that such step mayalso be performed after electrolytic recovery of lead. Regardless of anyoptional pre-processing, the lead ion-enriched solution is then fed toan electrolyzer to recover the lead in metallic form. While any type ofelectrolyzer is generally contemplated, especially preferredelectrolyzers will include those without separator or membrane betweenthe cathode and the anode, and with a cathode that moves relative to theelectrolyte. After reduction of the lead ions, the process will yield ahigh-purity lead (i.e., at least 98% purity, or at least 99% purity, orat least 99.5% purity). Where the electrolyzer has one or more movingelectrodes, and especially rotating disk electrodes, lead is beingdeposited as adherent but non-film forming lead.

An example of another embodiment of a method of the inventive conceptthat does not utilize a chelator is depicted schematically in FIG. 2. Asshown, a used lead acid battery is initially disassembled. Suchdisassembly can be ordered, for example by splitting or cutting alongedges and/or seems of the case and segregation of solid and liquidcomponents). Alternatively, disassembly can be carried out by crushing,grinding, fragmenting, and/or shredding to provide particulates fallingwithin the size ranges described above. Liquid and solid (e.g. plastic,metallic lead, lead paste) components can be separated by decantationand/or density. Certain components, such as sulfuric acid, plastic, andmetallic lead can be recovered directly in a form that is substantiallyready for re-use. Insoluble lead paste, containing active material leadspecies (e.g. lead sulfate and lead oxides) is collected for furthertreatment in a base treatment vessel 210.

Within the base treatment vessel 210 the lead paste is contacted with abase (NaOH in this example) that acts to generated lead hydroxide and asoluble sulfate salt from the lead sulfate component. Suitable basesinclude metal hydroxides (M_(x)(OH)_(y)) for which the correspondingmetal sulfate (M_(a)(SO4)_(b)) is soluble. Suitable examples includeGroup I metal hydroxides (such as LiOH, NaOH, and KOH). Other bases thatprovide soluble sulfate salts (i.e. soluble at greater than or equal to10, 25, 50, 75, 100, 200, 400, 600, or 800 or more g/L) and insoluble(i.e. insoluble at 10, 3, 1, 0.3, 0.1, 0.03, 0.01 or less g/L) leadsalts on reaction with Pb(SO₄), for example carbonates (such as Na₂(CO₃)and K₂(CO₃)), are also suitable. It should also be appreciated that suchbases can be used to rinse or otherwise clean plastic and metallic leadcomponents recovered from a lead acid battery in order to dislodge andrecover adhering lead sulfate containing paste, as part of thedisassembly process.

From the base treatment vessel 210 a supernatant 220 containing asoluble sulfate salt (depicted as sodium sulfate in this example) and aprecipitate 240 containing lead hydroxide and lead oxides are separatedand individually recovered. Separation of the sulfate-containingsupernatant 220 from the lead-containing precipitate 240 can beperformed by any suitable method. For example, the supernatant 220 canbe separated from the precipitate 240 by settling, centrifugalseparation (for example in a hydrocyclone), and/or filtration. Suitablefilters include filtration membranes and meshes, bed filters, pressfilters, and belt filters. Preferred separation methods are selected toefficiently separate the solid precipitate 240 from the supernatant 220while facilitating recovery of the precipitate for subsequentprocessing.

The supernatant 220 can be processed to generate sulfuric acid andregenerate the base used in the treatment of the lead paste recoveredfrom the recycled battery. This can be accomplished through the use ofan electrochemical cell 230. For example, when NaOH is used as the base,plating of sodium metal onto the cathode results in the formation ofNaOH on reaction with water. This regenerated NaOH can be recovered andreturned to the base treatment vessel 210 for extraction of lead pasteas part of a closed loop system. Similarly H₂SO₄ can be recovered fromthe anode, and subsequently used in any number of industrial processes.In a preferred embodiment, the recovered sulfuric acid is utilized inthe manufacture of lead acid batteries. Any suitable configuration ofelectrochemical cells can be used. In a preferred embodiment theelectrochemical cell is configured as a channel containing a segmentedanode and a segmented cathode arranged along its length, whereindividual electrode segment pairs are individually controllable (asdescribed in U.S. Pat. No. 8,580,414, to Clarke). Such an arrangementadvantageously permits single-pass processing at high efficiency.

Precipitate 240 recovered from the base treatment vessel 210 (i.e. basetreated active material lead) is dissolved in an alkane sulfonic acid(in this example, MSA). It should be appreciated that, with the removalof sulfate from the active material lead species, a chelator is notrequired when suitable base treatment of the lead paste is utilized. MSAcontaining solvated lead ions is treated in an electrodeposition cell250, as described above. Depletion of lead ions from the alkane sulfonicacid solvent effectively regenerates the solvent, permitting its re-usein solvating the base treated active material lead. Metallic lead (Pb(0)collected by electrodeposition can be collected from a collectioncathode of the electrodeposition cell 250 (for example, by scraping) andutilized in any number of industrial processes. As shown in FIG. 2, thematerials recovered from an old lead acid battery can be utilized in theconstruction of a new lead acid battery with no or essentially no netconsumption of either base or alkane sulfonic acid solvent, providing aclosed loop system for recycling of such batteries that does not utilizea smelting step. Further aspects of contemplated integrated processesand devices are taught in copending US provisional application with thetitle “Closed Loop Systems And Methods For Recycling Lead AcidBatteries”, filed on May 13, 2015.

Surprisingly, the inventors discovered that the metallic lead wasrecovered from processes of the inventive concept in the form of amicro- or nanoporous mixed matrix in which the lead formed micro- ornanometer sized structures (typically needles/wires) that trapped someof the electroprocessing/electrodeposition solvent and a substantialquantity of molecular hydrogen (i.e., H₂). Most notably, such a matrixhad a black appearance and a remarkably low bulk density. Indeed, inmost of the experimental test runs the matrix was observed to float onthe solvent and had a density of less than 1 g/cm3. Upon pressing thematrix or application of other force, the density increased (e.g., 1-3g/cm3, or 3-5 g/cm3, or higher) and a metallic silvery sheen appeared.

Additionally, it was unexpectedly observed that the reduced lead ionsdid not form a tightly bonded film on the cathode, but could be readilyremoved from the cathode by simply wiping the cathode with a material towhich the lead could adhere (e.g., plastic, lead-film, etc.). Therefore,lead recovery can be performed in a continuous manner. Particularlywhere a rotating or reciprocating electrode was employed, lead ionscould be reduced one part of an electrode or electrode assembly, whilemetallic lead can be removed from another part of the electrode orelectrode assembly. Especially suitable cathodes and aspects thereof aretaught in co-pending US provisional application with the title“ApparatusAnd Method For Electrodeposition Of Metals On Aluminum Cathodes”, filedon May 13, 2015.

As noted above, an electroprocessing solvent can be reused aftersufficient quantities of lead had been removed via reduction. It shouldbe recognized that in processes utilizing alkane sulfonic acid+chelatorelectroprocessing solvents, electrodeposition of metallic lead canresults=in the accumulation of sulfate in the solvent. Spentelectroprocessing solvent could be processed by mechanical processing(e.g., filter, centrifuge, hydrocyclone, etc.) to remove any solids,and/or chemical processing (e.g., by precipitation of sulfates, forexample, to produce calcium or strontium sulfate), and/or adsorptiveprocessing (e.g., activated charcoal, ion exchange resin, etc.) can beutilized to reduce or eliminate accumulated sulfate. Thus,electroprocessing solvents utilized in electrodeposition processes canbe reused in the next cycle of processing lead materials for both alkanesulfonic acid and alkane sulfonic acid+chelator solvent systems.

With respect to the alkane sulfonic acid it should be appreciated thatnumerous alkane sulfonic acids are deemed suitable for use herein.However, MSA is especially preferred as this compound is environmentallyfriendly and stable under electrolytic conditions used. However, othersuitable alkane sulfonic acids include ethyl sulfonate, proplyenesulfonate, trifluro methyl sulfonate (triflic acid), sulfamic acid, etc.In most circumstances, the MSA or other alkane sulfonic acid will bepresent in a significant concentration, typically at least 1-5 wt %,more typically 5-15 wt %, even more typically 25-50 wt %, and mosttypically between 15 and 35 wt % of the electroprocessing solvent. Thus,suitable concentrations will typically be between 5 and 50 wt %, orbetween 20 and 30 wt % of the electroprocessing solvent. The pH of theelectroprocessing solvent is most preferably acidic as noted above, andmost typically between pH 5-7, or between pH 1-3, or between pH 3-5.Viewed form a different perspective, the pH of the electroprocessingsolvent will be less than 7, or equal or less than 5, or equal or lessthan 3.

Similarly, the nature of the chelator may vary considerably. However, itis generally preferred that the chelator is a chelator that is selectiveor preferential for divalent cations. Therefore, EDTA may be partiallyor completely replaced by other chelating agents such as NTA(nitrilotriacetic acid), IDA (iminodiacetic acid), DTPA(diethylenetriaminepentaacetic acid), etc. Regardless of the particulartype of chelator, it is preferred that the chelator is typically presentin an amount of at least 0.1-1 wt %, more typically 1-3 wt %, even moretypically 3-10 wt %, and most typically between 2 and 8 wt % of theelectroprocessing solvent. Furthermore, it is noted that the chelatormay be provided in form of a salt where the chelator has otherwisereduced solubility in acidic solution (e.g., Na₂-EDTA). It should benoted that such concentrations may even exceed the solubility limit ofthe chelator. Suitable solvent are preferably aqueous and will mostpreferably be prepared from deionized water. However, additionalco-solvents are also deemed suitable and include alcohols, variouspolyols (propylene glycol, polyethylene glycol, etc.), etc.

Of course, it should be noted that the particular size/dimensions of theelectrolytic cell may vary considerably and that the specific processconditions and operating parameters will at least in part determine thesize and volume of the electrolytic cell. In especially preferredaspects, however, the electrolytic cell is operable without the need fora membrane separator. Viewed from another perspective, the cell need notbe separated in fluidly distinct catholyte and anolyte compartments.Moreover, it should be appreciated that the electrolytic cell need onlybe fluidly coupled to the container in which the lead materials orbase-treated active lead materials are being dissolved. Where treatmentof the electroprocessing solvent is considered, it should be noted thatthe type of treatment will determine the location of such treatmentunit, and that the skilled artisan will be readily appraised of thesuitable location. However, preferred locations are those wheretreatment is performed on the lead ion-enriched solvent or the at leastpartially depleted solvent. As used herein, and unless the contextdictates otherwise, the term “coupled to” is intended to include bothdirect coupling (in which two elements that are coupled to each othercontact each other) and indirect coupling (in which at least oneadditional element is located between the two elements). Therefore, theterms “coupled to” and “coupled with” are used synonymously.

In other contemplated aspects of the inventive subject matter, and withfurther respect to the electrodes in the electrolyzer/electrodepositionunit it should be appreciated that numerous electrodes are deemedsuitable for use herein. Indeed, it should be noted that all conductivematerials are considered suitable for use in conjunction with theteachings herein so long as such materials are compatible with theelectrochemical conditions use in the process. Therefore, and amongother contemplated materials, suitable anodes include various metals,carbon (typically graphite, glassy carbon, or graphene) anodes, matricescomprising at least one polymer and one form of carbon and especiallypreferred anodes will be titanium anodes, which may be coated withruthenium oxide (or other metal oxide). Notably, aluminum has been foundnot to dissolve in the lead-ion enriched electroprocessing solvent andas such aluminum coated with a conducting and non-passivating materialsuch as ruthenium oxide is contemplated as an anode material.Alternatively Magneli Phase sub-oxides of titanium (of the formulaTixO(2x−1) where x is an integer between 4 and 11) have been discoveredto be stable anode materials in electrolytes of similar composition tothe electroprocessing solvent and are contemplated for use as anodematerials and passivation resistant coatings on anodes.

More notably, however, the inventors discovered that the lead recoveryprocess, when using the lead ion-enriched electroprocessing solventsdisclosed herein, lead to the formation of a low density leadcomposition that included lead at a very high purity and that includedsome of the solvent and hydrogen produced at the cathode. Mostremarkably, most if not all of the so formed lead composition was blackin color, did not plate and bond as an electrochemically bound film tothe cathode, but rather floated onto the surface upon moderate to strongagitation of the solvent. When pressed into a smaller volume, hydrogenand electroprocessing solvent were expelled and the remaining leadreturned to a metallic appearance. Unexpectedly, less than 10% (e.g.,between 5-9%), more typically less than 7% (e.g., between 2-6%), evenmore typically less than 5% (e.g., between 1-4%), and most typicallyless than 3% (e.g., between 0.01-2%) of the total lead formed at thecathode was found as plated and strongly adherent lead on the cathode,while the remainder of the lead remained in the low density form. Whilenot wishing to be bound by any theory or hypothesis, the inventorscontemplate that the lead in the low density lead materials formed amicro- or nanoporous mixed matrix comprising micrometer or evennanometer-sized lead filaments to form a porous material in whichhydrogen and the solvent were trapped.

Upon further study, the inventors noted that low density and high-puritylead could be obtained from multiple cathode materials, regardless ofcathode shape or relative movement of the solvent against the cathode.However, vigorous agitation or movement of the cathode relative to theelectroprocessing solvent did simplify ‘harvest’ of the floating lowdensity lead composition. Therefore, and among other suitable choices,preferred cathode materials include various metals, and especiallyaluminum. Alternatively, carbon (e.g. graphite, diamond like carbon,graphene, etc.,) matrices comprising at least one polymer and one formof carbon, Magneli Phase sub-oxides of titanium (of the formulaTixO(2x−1) where x is an integer between 4 and 11) have been discoveredto be stable cathodes materials in the electroprocessing solvent and arecontemplated for use as cathode surfaces.

While a lack of plating is typically undesirable in all or mostelectrowinning methods, the inventors now discovered that such lack ofplating will enable a continuous lead recycling process in which leadcan be continuously removed from the cathode on one segment whileadditional lead is formed on another segment of the cathode. Removal ofthe adherent/weakly associated lead is typically done using a mechanicalimplement (e.g., a wiping surface, blade, or other tool in closeproximity to the cathode, etc.), however, removal can also be performedvia non-mechanical tools (e.g., via jetting electroprocessing solventagainst the cathode, or sparging gas against the cathode, etc.).Moreover, it should be noted that the removal may not use an implementat all, but merely by done by passive release of the low density leadmaterial from the cathode and flotation to the surface of theelectrochemical cell (where an overflow weir or harvesting will receivethe lead materials).

Therefore, in at least some preferred aspects, the cathode comprises oneor more disk-shaped aluminum cathodes that are rotatably coupled to theelectrolytic cell and that are in close proximity to the cathode(s).FIG. 3A is a photograph of a small-scale experimental electrochemicaldevice in which lead acid battery scrap materials (predominantly gridlead and active materials lead) are contacted in a digestion tank. Solidmaterials are then removed as needed and the lead ion enrichedelectroprocessing solvent is then fed into the electrolytic cell wherelow density lead materials are plated on the disk shaped electrode.

In processes that utilize an alkane sulfonic acid+chelatorelectroprocessing solvent and that do not utilize a base treatment stepfor removal of sulfate from the active lead species, at least a portionof the electroprocessing solvent is fed to the recovery unit in which anion exchange resin and a precipitation stage periodically remove sulfateions and other non-metal ions.

FIG. 3B is a photograph showing a more detailed view of a pair ofdisk-shaped cathodes and wiper surface that is proximally positioned tothe cathodes to so wipe the low-density lead material from the cathodesurface in a non-peeling manner (i.e., without lifting a coherent leadsheet or coherent lead film from the cathode in a pulling motion). FIG.1C is more schematic exemplary depiction of anelectrolyzer/electrodeposition unit according to the inventive subjectmatter where electrolyzer 100 has a cell 110 that contains a leadion-enriched electroprocessing solvent 112. Anode 120 and rotatingdisk-shaped cathode 130 are at least partially disposed in the cell tocontact the lead ion-enriched electroprocessing solvent 112 and topromote formation of low density lead product 142 that is taken up bylead harvester 140 (typically a plastic wiper or otherwise proximallypositioned surface).

Of course, it should be appreciated that the inventive subject matter isnot limited to use of a disk-shaped electrode, but that in fact allelectrodes are deemed suitable that allow active (e.g., using a wipingblade or surface) or passive removal (e.g., via bubbles, solventjetting, or flotation) of high-purity lead from the cathode. Thus,suitable electrodes may be configured as simple plates that may bestatic relative to the solvent or moved in a reciprocal manner, orelectrodes that can be continuously moved and that are configured toallow reduction of lead ions on one portion and lead removal on anotherportion. For example, suitable electrode configurations includeconductive disks, cylinders, spheres, belts, etc. Likewise, it should berecognized that the number of cathodes may vary considerably, and thatmost typically multiple cathodes are operated in parallel (or serially,especially where the cathodes are static relative to the solvent.

Notably, the inventors realized that cell 110 can be operated withoutsignificant anodic destruction (e.g., less than 10% chelator loss per 12hours of continuous operation) of a chelator of an alkane sulfonicacid+chelator electroprocessing solvent, even in the absence a membraneor other separator. Solvent conditioning unit 150 for removal of sulfateis fluidly coupled to the cell to receive solvent and provide backconditioned solvent in embodiments where removal of accumulated sulfatefrom the electroprocessing solvent is needed. Solvent processing can beperformed in numerous manners and may be continuous or batch-wise. Mosttypically, processing the solvent includes a step of filtering to removeat least some of the particulates, a step of sulfate removal (e.g., vialime precipitation, reverse osmosis, ion exchange, electro-osmosis, saltsplitting, liquid chromatography, liquid/liquid extraction etc.,),and/or a step of non-lead metal ion removal (e.g., ion exchange). Wherethe process is operated in a batch mode, collection of multiple streamsof solvent is especially preferred, and a surge or holding tank maytherefore be added to the system. On the other hand, where the system iscontinuously operated, multiple streams may be combined and thenprocessed to reduce redundancy and plot space.

Lastly, with respect to the grid lead recovered from the leadion-enriched solvent, it should be noted that the grid lead may bewashed (for example with base or with an alkane sulfonic acid+chelatorsolvent), compacted, and ingoted or be further refined to increasepurity where desired. Residual plastic materials are preferablycollected from the scrapping operation and recycled in a separateprocess stream using conventional plastic recycling methods.

It should be appreciated that the described processes can be performedin a batch manner, in which a single bolus of lead paste is processed toproduce a discrete batch of soluble sulfate salt and a discrete batch oflead-containing precipitate. Using suitable separation methods, however,processes of the inventive concept can be performed in a continuousfashion, with a stream of lead paste being processed to produce streamsof sulfuric acid and precipitate. In some embodiments processes of theinventive concept can be performed in a semi-continuous manner, forexample by providing discrete boluses of lead paste in succession.

EXPERIMENTAL DATA AND CONSIDERATIONS

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.“such as”) provided with respect to certain embodiments herein isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention otherwise claimed. No languagein the specification should be construed as indicating any non-claimedelement essential to the practice of the invention.

In a first set of experiments, the inventors investigated the ability ofa solvent to digest various components of a lead acid battery and in asecond set of experiments to investigate the ability to electroplate orreduce the dissolved lead (optionally after filtration). Digestion ofthe various components was initially carried out using only MSA inconcentrations ranging from 1-50 wt %. At all concentrations themajority of the lead oxides were extremely soluble. However, theinventors did not attempt to isolate and test insoluble forms of PbO₂ inthe initial work because it was quickly apparent that lead sulfate(PbSO₄) did not digest very well. Although soluble, the overallconcentration of lead sulfate was low (as measured by solution density),the rate of digestion was also slow (upwards of 24 hours), and digestionrequired agitation and heat. With the addition of disodiumethylenediamine tetraacetic acid (EDTA), both the concentration anddigestion rate were vastly improved. The density increased from 1.2g/cm³ to greater than 2.1 g/cm³. More importantly and unexpectedly, leadwas easily electroplated/reduced from this solution, in acid conditionsand without the need for a membrane.

In a preferred set of experiments, the MSA concentration wasapproximately 25 wt % (+/−5) MSA in combination with approximately 5 wt% disodium EDTA. For example, a typical solution was made up as follows:100 L of 98% MSA, 20 kg of disodium EDTA, the remainder of water filledto 450 L total volume. However, the actual amounts used may vary by asmuch as 10%. Notably, this solution was able to digest approximately 33kg of mixed battery materials in a 12 hour period without heating orsignificant agitation. The starting density was 1.1 g/cm³ and themaximum density achieved was 1.6 g/cm³. It should be appreciated thatsome of the EDTA did not dissolve (possibly due to reaching saturationconcentration in the acidic solution), and it is estimated that about 2to 5 kg of the disodium EDTA did not fully dissolve and was captured astank scaling or on the filters during recirculation. Therefore, in mostpractical examples, preferred electroprocessing solvents will include20-30% MSA, 2-8% EDTA, with the remainder deionized water.

Remarkably, the bulk of lead oxide and sulfate are highly soluble incontemplated electroprocessing solvents while metallic lead (and solidlead alloys from lead grids) did not dissolve and was stripped clean ofcontamination; under most experimental conditions, 60-90% currentefficiency was observed with a low voltage needed. Due to selectivedissolving of the positive and negative active materials (PAM and NAM),substantially less energy for overall lead recycling is required.

Using a reclamation set up as shown in FIG. 3A, and a total sweptcathode area of 0.252 m² and a tank size 10 US gallon, the followingdata in Table 1 and 2 were obtained:

TABLE 1 A/m2 Batch Run RPM Scraper A Cathode Vi Vf T 1 1 5.00 on 50.00197.72 3.00 3.50 10.00 1 2 5.00 on 100.00 395.44 3.90 4.10 10.00 1 35.00 on 150.00 593.16 4.40 4.60 10.00 1 4 5.00 on 50.00 197.72 3.10 3.4010.00 2 1 5.00 on 150.00 593.16 4.40 4.50 5.00 2 2 5.00 on 150.00 593.164.50 4.50 5.00 2 3 10.00 on 150.00 593.16 4.50 4.60 5.00 3 1 10.00 on100.00 395.44 3.70 3.80 5.00 3 2 10.00 on 100.00 395.44 3.80 4.10 5.00 33 10.00 on 100.00 395.44 3.90 4.10 5.00 3 4 10.00 on 215.00 850.20 5.005.00 5.00 3 5 2.00 on 100.00 395.44 3.80 3.80 5.00 3 6 1.00 at end 93.00367.76 3.80 3.80 5.00 3 7 1.00 at end 90.00 355.90 3.80 3.80 5.00 4 11.00 at end 400.00 1581.76 6.40 6.60 5.00 5 1 1.00 at end 200.00 790.884.60 4.60 5.00 5 2 on 200.00 790.88 4.80 4.80 5.00 5 3 on 200.00 790.884.70 4.70 5.00 5 4 on 200.00 790.88 4.80 4.80 5.00 5 5 on 200.00 790.884.60 4.60 6.20 5 6 on 200.00 790.88 4.70 4.70 5.00 5 7 on 200.00 790.884.70 4.70 5.00

TABLE 2 Pb (g/l) CE % Batch Run wet g dry g g/hr g/Ah kg/h/m2 at startTheory 1 1 30.41 182.43 3.65 0.72 10.03 0.96 1 2 50.39 302.32 3.02 1.209.22 0.80 1 3 49.69 298.14 1.99 1.18 7.89 0.52 1 4 32.89 22.37 134.242.68 0.53 6.58 0.71 2 1 48.77 31.17 374.04 2.49 1.48 10.03 0.66 2 240.77 28.74 344.88 2.30 1.36 9.27 0.61 2 3 40.26 29.47 353.64 2.36 1.408.49 0.62 3 1 22.18 266.16 2.66 1.05 10.03 0.70 3 2 26.64 319.68 3.201.26 9.44 0.84 3 3 20.82 249.84 2.50 0.99 8.74 0.66 3 4 37.78 453.362.11 1.79 8.19 0.57 3 5 20.30 243.60 2.44 0.96 7.19 0.66 3 6 12.70152.40 1.64 0.60 6.66 0.43 3 7 10.38 124.56 1.38 0.49 6.32 0.36 4 156.79 681.48 1.70 2.69 10.03 0.45 5 1 33.80 405.60 2.03 1.60 10.03 0.535 2 34.50 414.00 2.07 1.64 9.12 0.55 5 3 30.48 365.76 1.83 1.45 8.310.48 5 4 28.40 340.80 1.70 1.35 7.56 0.45 5 5 31.70 306.77 1.53 1.216.73 0.40 5 6 22.90 274.80 1.37 1.09 6.12 0.36 5 7 20.50 246.00 1.230.97 5.58 0.32Efficiencies for plating are depicted in FIGS. 4A-4C, wherein FIG. 4Ashows the current efficiency of lead production as a function of theinitial lead concentration at 200 A at a current density of 790 A/m² and1 rpm of the disk cathode. FIG. 4B shows the current efficiency as afunction of electrode current density, and FIG. 4C plotted currentefficiency against lead concentration.

As is shown in Table 3 below, high purity lead was obtained at thecathode as a micro- or nanoporous mixed matrix having a density of lessthan 1 g/cm³ (floating on the surface of the solvent). Moreover, thelead composition did not plate on the cathode as a solid and coherentfilm but was recovered as amorphous soft and compressible mixed materialthat contained the methane sulfonic acid and hydrogen.

TABLE 3 Element Quant. Det. Limit Actual Bismuth ppm, (μg/g) 0.1 1.3Copper ppm, (μg/g) 0.1 1.1 Lead ppm, (μg/g) 0.1 Major (99.5%+) Potassiumppm, (μg/g) 0.5 18 Sodium ppm, (μg/g) 0.1 0.20 Tin ppm, (μg/g) 0.2 30

Notably, the so obtained mixed material was different from conventionalsponge lead that is normally produced using foaming agents or gasinjection during cooling of liquid lead that was previously purified.

It should be appreciated that methods and reagents of the inventiveconcept, while described above in terms of recycling of lead acidbatteries, can also be applied to the recovery of sulfate from othersources. Suitable alternative sources include sulfate-containing saltswith corresponding insoluble hydroxides or, alternatively, unstablehydroxides that form insoluble oxides. Examples of sulfate-containingmaterials from which sulfate can be extracted include materials thatinclude sulfate salts of Group II elements, transition metals, andaluminum.

It should be apparent to those skilled in the art that many moremodifications besides those already described are possible withoutdeparting from the inventive concepts herein. The inventive subjectmatter, therefore, is not to be restricted except in the spirit of theappended claims. Moreover, in interpreting both the specification andthe claims, all terms should be interpreted in the broadest possiblemanner consistent with the context. In particular, the terms “comprises”and “comprising” should be interpreted as referring to elements,components, or steps in a non-exclusive manner, indicating that thereferenced elements, components, or steps may be present, or utilized,or combined with other elements, components, or steps that are notexpressly referenced. Where the specification claims refers to at leastone of something selected from the group consisting of A, B, C . . . andN, the text should be interpreted as requiring only one element from thegroup, not A plus N, or B plus N, etc.

What is claimed is:
 1. A method of continuously and electrochemicallyproducing high-purity lead from a lead ion-enriched electroprocessingsolvent, comprising: treating active lead materials with a base togenerate base-treated active lead material that includes lead oxides andlead hydroxides; dissolving the base-treated active lead material leadin an electroprocessing solvent to so form a lead ion-enrichedelectroprocessing solvent, wherein the electroprocessing solventcomprises an alkane sulfonic acid and does not include a chelator;reducing lead ions in the lead ion-enriched electroprocessing solvent ona cathode to form adherent, high-purity lead and a regeneratedelectroprocessing solvent wherein high-purity lead is loosely attachedto the cathode and produced as a micro- or nanoporous mixed matrixenclosing molecular hydrogen (H₂) and the electroprocessing solvent andwherein the high-purity lead has a purity of at least 99.5%, wherein thecathode comprises aluminum; removing the adherent high-purity lead fromone portion of the cathode while lead ions are reduced on anotherportion of the cathode, wherein the cathode is moved relative to thelead ion-enriched electroprocessing solvent during the step of reducingthe lead ions; contacting at least some of the regeneratedelectroprocessing solvent with additional active lead materials to soproduce at least a portion of the lead ion-enriched electroprocessingsolvent.
 2. The method of claim 1 wherein the step of treating theactive lead materials with the base generates a solution comprising asoluble sulfate salt.
 3. The method of claim 2, further comprising astep of recovering base from the solution as a recycled base, andutilizing at least a portion of the recycled base in the step oftreating the active lead materials.
 4. The method of claim 2, furthercomprising a step of subjecting the treated active lead materials to astep of settling, centrifugation, or filtration.
 5. The method of claim1 wherein the base is a sodium hydroxide solution or a sodium carbonatesolution.
 6. The method of claim 1 wherein the alkane sulfonic acid is amethane sulfonic acid, and wherein the alkane sulfonic acid in theelectroprocessing solvent has a concentration of between 15 and 35 wt %.7. The method of claim 1 wherein the cathode is configured as a rotatingdisk.
 8. The method of claim 1 wherein the adherent high-purity lead isremoved by a harvester surface in a non-peeling manner, and wherein theharvester surface is positioned proximal to the cathode.
 9. The methodas in claim 1, wherein the step of removing the adherent high-puritylead from one portion of the cathode is achieved using a removal toolpositioned in close proximity to the cathode but not in direct contacttherewith.
 10. The method as in claim 9, wherein the removal tool ispositioned between 0.5 and 5 mm away from the cathode.
 11. The method asin claim 1, wherein in the step of reducing the lead ions, the mixedmatrix has a density of less than 5 g/cm³.
 12. A method for recycling alead acid battery, comprising: obtaining a first quantity of lead pastefrom the lead acid battery, the lead paste comprising lead sulfate;contacting the first quantity of lead paste with a base, therebygenerating a supernatant and a first precipitate, wherein the firstprecipitate comprises lead hydroxide; processing the supernatant tothereby generate a second product stream comprising a regenerated base;contacting the first precipitate with an electroprocessing solvent togenerate a lead ion containing solution, wherein the solvent comprisesan alkane sulfonic acid and does not include a chelator; contacting thelead ion containing solution with a collection cathode, wherein thecollection cathode comprises aluminum; applying an electrical potentialto the collection cathode, thereby depositing adherent metallic leadloosely attached to the collection cathode and producing a third productstream comprising a regenerated electroprocessing solvent; wherein theadherent metallic lead is produced as a micro- or nanoporous mixedmatrix enclosing molecular hydrogen (H₂) and the electroprocessingsolvent, and wherein the lead has a purity of at least 99.5%; collectingthe adherent metallic lead from the collection cathode, wherein thecathode is moved relative to the electroprocessing solvent; contacting asecond quantity of lead paste with at least a portion of the secondproduct stream to generate a second precipitate; and contacting thesecond precipitate with at least a portion of the third product stream.13. The method of claim 12 wherein the step of processing comprises astep of settling, centrifugation, or filtration.
 14. The method of claim12 wherein the step of processing comprises a step of subjecting thesupernatant to electrolysis to thereby electrochemically produce sodiumhydroxide and sulfuric acid.
 15. The method of claim 12, wherein thesolvent solution comprises an alkane sulfonic acid and does not includea chelator.
 16. The method of claim 12 wherein the base is a sodiumhydroxide solution or a sodium carbonate solution.
 17. The method ofclaim 12 wherein the alkane sulfonic acid is a methane sulfonic acid,and wherein the alkane sulfonic acid in the electroprocessing solventhas a concentration of between 15 and 35 wt %.
 18. The method of claim12 wherein the collection cathode is a rotating or reciprocating cathodeon which lead ions are reduced on one part while metallic lead isremoved on another part.
 19. The method of claim 12 wherein the step ofcollecting the metallic lead uses a harvester surface in a non-peelingmanner, and wherein the harvester surface is positioned proximal to thecathode.